When one of Mimi Almeida's managers, who is black, considered quitting so he could move to London, the president of San Francisco event planning firm R/A Performance Group decided to open an office in the United Kingdom and create the position of creative director just to keep him onboard. For Almeida, having women and minorities in managerial positions on her 22-person staff is important, she says, because it's critical for maintaining good relations with her diverse client base. "In San Francisco, becoming diverse isn't necessarily the challenge," says Almeida, 53, whose business development manager is a Filipino woman. "It's maintaining diversity."

If trying to make and keep your management ranks diverse has you frustrated, you may have been going about it the wrong way. Most diversity initiatives, including the highly popular diversity training, don't work. That's the conclusion of a study conducted by three university researchers of decades' worth of employer data.

The scientists examined the government's employment figures for 708 companies from 1971 to 2002, then added survey information describing the companies' diversity programs. Training efforts and initiatives that evaluated managers on diversity results were the least effective ways of increasing the proportion of women and minorities in management. Mentoring and networking, which both seek to reduce isolation among female and minority managers, worked only modestly.

University of Arizona sociologist Alexandra Kalev, one of the study's authors, says the findings support previous research suggesting that a few days of training can't overcome deeply entrenched biases, and that basing evaluations on diversity achievements sometimes generates backlash, worsening the problem. While the study looked only at women and blacks, the findings should hold true for Asian Americans and Hispanics, she adds.

Kalev and her associates found one initiative that did work: placing responsibility for improving management diversity with a specific person or team. And it worked well. After putting a diversity task force in place, companies saw a 14 percent increase in white women managers, a 30 percent increase in black female managers and a 10 percent increase in black male managers. "Another thing is that combining different practices works best," Kalev adds. "For example, diversity training is more likely to be effective when there is a diversity officer." She cautions that the research doesn't indicate that training should be abandoned, but rather that it shouldn't be expected to do the job on its own.

Assigning the diversity challenge to an individual or task force succeeds because it means someone is constantly evaluating objectives, monitoring progress and trying to make improvements, Kalev says: "When there is internal oversight and accountability, things are more likely to work."

Mark Henricks writes on business and technology for leading publications and is author of Not Just a Living.